If you make multiple sounds in sounds.json point to one audio file, only the first definition works, and the rest are ignored:

{  
  "ambient.cave.cave": {
    "category": "ambient", "subtitle": "Test",
    "sounds": ["test"]
    },
  "ambient.weather.rain": {
    "category": "weather", "subtitle": "Test 2",
    "sounds": ["test"]
    }
}

If you try using /playsound on ambient.cave.cave, it works fine, however ambient.weather.rain has no changes.